1) Pure Advantage methyl-B12 spray - ineffective (I wonder about the sorbate preservative in it); 2) InterPlexus Inc NutriSorb liquid hydroxycobalamin - effective but still needs to be 'converted' to active form - I found the one drop dose suggested on label isn't enough; 3) Solgar cyanocobalamin 1mg sublingual - dissolves too fast and not as effective as active methyl-B12; 4) Natural Factors methyl-B12 1mg sublingual - dissolves too fast under tongue but found it better inbetween gum/lip where it will sit and dissolve more slowly. Iodine/B12 are synergists - suggest adding/increasing either one if taking more of the other, especially long term. Same is true of other nutrients such as manganese and zinc (both need cobalt, high cobalt may deplete them) - could be why some people note headaches after taking high doses of B12 (both high and low manganese can cause migraine-headaches). High doses of B12 will also deplete iron - they are antagonists. If this review was helpful to you, please click YES below - thank you. For reviews of all the products I have purchased from iHerb, please click my username above.

The roles B-12 play in the body are numerous and vital. Vegetarians in particular (and especially vegans) should take this supplement, even if they are of the mindset that vitamin pills are silly, because B-12 is found almost exclusively in animal products. Additionally, it is difficult for some to absorb (the elderly and some with various health conditions) as it is only absorbed in one part of the intestine. Finally, alcohol consumption creates a situation where extra supplemental B-12 is beneficial.
Anyway, about this product in particular. I have always liked the brand Source Naturals as they make my favorite multiple, which is why I purchased this. It seems to fit the bill. It's the MethylCobalamin type (which is the preferred structure), and they are sublingual (which aids in absorption), and it is an adequately large dose (1mg, which is about 16000% of the RDA). The tablets dissolve slower than other brands I've used, which can be slightly annoying, but the company claims that this is for better absorption. Overall, a fairly decent product, with a light pleasant cherry taste.

Combined with extra B6, the Life Force Multiple and some fish oil, this B12 contributed to the elimination of chronic back pain, depression, arthritis, carpal tunnel syndrom. Source Naturals is a quality manufacturer.

I actually ordered this product from an online retailer in Europe because I had just discovered I was anaemic due to B12 deficiency and wanted the tablets fast. The customs here in Germany have sometimes held back iherb.com deliveries, resulting in my having to pick them up from the local branch of the customs office about four weeks after placing my original order. So this time I didn't use iherb.com, although their prices are unbeatable.
At any rate, this product worked FANTASTICALLY for me!!! The fact that it takes longer to dissolve is actually a GOOD THING, as you will then absorb more of the B12. I felt better within a few days of taking this and, now, after just over a month of taking this product, I feel almost back to normal. I can walk again at my normal speed, my energy levels are back with a vengeance, I feel like my normal self again!!!
My B12 levels were 477, which here was classifed as fine. However, in Japan and elsewhere in Europe, levels below 500 are seen as deficient. Apparently, a good level is around 1100-1300!!!
I am sure that these work and the criticism voiced by some reviewers that they take &quot;too long&quot; to dissolve can be dismissed. I have some other B12 tablets and I don't feel that they work half as well and will never order them again. They disappear within seconds and that means you're not absorbing much.
Edited to add the following, Dec 2011
Well, I think I may have to sound less euphoric this time. I recently had my B12 levels tested and they hadn't gone up significantly at all, just to just above 500, rather than just under 500, as reported above. I am now taking the Jarrow Formulas 5mg tablets as they seem to have good results. I genuinely felt better, so I believe it is a good product. It is possible that I have thyroid issues which may have affected my B12 levels. I am also perimenopausal and this may also have had an influence. At any rate, I'm now trying the 5mg tablets and will report back when I next get blood work done.

Was happy to find a sublingual methlycobalmin supplement that tastes fine, just what I was looking for. Have since learned that hydroxycobalmin is actually the best form of vitamin B12 and will buy that next time.